Abstract
The drawbacks of the usual explanation of the influence of pH and salt composition on partition of polyelectrolytes in aqueous polymer two-phase systems are outlined. An explanation is presented that avoids the introduction of thermodynamic data on single ions and of single potential differences. It leads to an equation that describes the relation between the ratio of the partition coefficients of a polyelectrolyte in the presence of either of two salts on one hand, and its charge and the partition coefficients of the involved salts on the other. Examples of the application of this equation to literature data are given.